package 期末练习;

public class Circle {
    double r;


    public void area() {
        double pai = 3.14;
        double s = pai * r * r;
        System.out.println("面积为" + s);
    }
    public void area2(double pai) {
        double s = pai * r * r;
        System.out.println("面积为" + s);
    }
    public double area3(double r ,double pai){

        double s = pai *r*r;

        return s;


    }

}
